Since there is no card to swipe yet at Walmart the options are initially limited to buying a $5 MoneyPak, Bank ACH which will take a few days or a debit card. It seems you can use a credit card also but they caution that you could be charged by the CC company for doing so.
The opening deposit has to be $50 or more. Once you have a card in hand cash deposits are free of charge at any WalMart register.
If you do fund your GoBank account initially with a MoneyPak they credit you the $4.95 fee right away - good deal.